hi all..im new here so a big hello...now down to buisness...i have a 93 f 250 5.8...i got a tps code so i went to make sure it was adjusted properly or if it was bad..i have done this on both my mustangs and many other fords...im not new to tps adjustment...heres the problem..at idle position the sensor only read 0.12 volts and at full throttle it only reads 1.27 volts...i know it should be around 0.98 to 0.99 with the engine not running and at full open 4.50 to 5 volts...i tried taking it off the throttle body,sticking a volt meter to it and fully opening it and can only get 1.27 volts...when i probe the orange wire i get 5 volts steady...i know there is something wrong....any clues...my truck is also idleing rough and sputters at very little throttle but is find half throttle and up to full..and the idle is very low all of the sudden..starts great high idles like normal for a few then drops almost killing the engine...thanks for any help

 

Well it certainly isn't working right. When you open it it should get close to 5V and closed it should read .5v-1v. Although it doesn't seem right that it works good at WOT it is definitely not working right and replacing it should fix the issue.

 

i tried replacing it and i still only get 1.27 volts max!theres nothing wrong with the tps i tried 3 of them...could the computer be a problem and not giving the right voltage to the tps plug?????

 

If your input voltage is right the output should be correct also unless of course the TPS is bad but you said you have tried 3 now. Are you probing the return wire and the ground wire, not the frame ground or battery?

 

What are you attaching the negative probe to?

 

ive tried grounding at the plug,at a main ground junction,and at the battery and they all read the same..i just went and checked the tps on my mustang and it comes up perfect..theres something wrong with the voltage coming to the tps on this truck

 

Didn't you say that you get 5V on the power in? If so the only thing that could be wrong is the TPS... Try the one off that mustang. It's always possible that the new ones are bad. Perhaps the TPS is right. That dieing idle could also be cause by a clogged IAC, either way cleaning it out won't hurt. Then it wont leave you stranded for another 50k.

 

thanks for the help guys..i will try the IAC

 

Have you tried checking for a short between the TPS signal wire and ground with the sensor unplugged?

 

Is it possible to bench test a tps before actually installing or plugging it in

 

You cannot test voltage without any volts.

However you can test the resistance levels of the sensor.

 

Try backprobing the TPS connector when it's hooked up to the truck- it's possible the 5v supply
in the PCM has gone soft, and can't hold 5v across the TPS... so it meters OK when the TPS is unplugged,
but when you plug it in it gets dragged down to 1.27v. Or there's a corroded connection at the PCM, or sum'fin...

t

 

they are a wear part, like spark plugs and glow plugs, and can develop dead spots in them. Best to replace, they aren’t that spendy.

 

​​​​​It's a $70-$100 sensor, I'd say that's worth testing.

 

Really? I replaced mine three days ago. $27 shipped. Amazon. Worked great, just touchy to dial in. I run 1.82vdc @ idle, 3.96vdc @ wot